Current Directions in Psychological Science

Theoretical Speculations on the Evolutionary Origins of Hemispheric Specialization

Abstract

Hemispheric specialization has long been considered a uniquely human trait associated with the evolution of language and handedness. Recent studies in a host of vertebrate species have reported evidence of population-level behavioral and brain asymmetries, challenging the claims for the uniqueness of hemispheric specialization to the human species. Here we summarize the findings in nonhuman species and discuss the adaptive significance and potential costs of lateralization of function.